The present disclosure relates generally to optical imaging systems and in particular to sensor systems with multiple sensor channels tuned to different light characteristics or properties and that include sensor channels usable for ranging.
Light imaging, detection and ranging (LIDAR) systems measure distance to a target by illuminating the target with a pulsed laser light and measuring the reflected pulses with a sensor. Time-of-flight measurements can then be used to make a digital 3D-representation of the target. LIDAR systems can be used for a variety of applications where 3D depth images are useful including archaeology, geography, geology, forestry, mapping, construction, medical imaging, and military applications, among others. Autonomous vehicles can also use LIDAR for obstacle detection and avoidance as well as vehicle navigation.
In applications such as vehicle navigation, depth information (e.g., distance to objects in the environment) is extremely useful but not sufficient to avoid hazards and navigate safely. It is also necessary to identify specific objects, e.g., traffic signals, lane markings, moving objects that may intersect the vehicle's path of travel, and so on. Accordingly, systems such as autonomous vehicles may include both a LIDAR system and another imaging system, such as a visible-light camera that can capture ambient light, including reflected light from objects in the environment as well as direct light from any light source that may be present in the environment. Each imaging system (LIDAR and visible-light) independently provides an image containing either depth or spectral data. For some applications, it is beneficial to align the different images with each other, e.g., by performing image registration to identify the position of the same object in different images. Image registration can be a complex and computationally intensive task. For instance, different imaging systems may have different resolutions and/or frame boundaries, and the alignment between independently constructed and/or independently controlled imaging systems may be inexact.